The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
An aircraft is moved by several propulsion units each comprising a turbojet engine housed in a nacelle. A nacelle generally has a tubular structure along a longitudinal axis comprising a fixed upstream section constituted by an air inlet upstream of the turbojet engine, a fixed mid-section intended to surround a fan of the turbojet engine, and a downstream section accommodating thrust reversal means and intended to surround the combustion chamber of the turbojet engine, the upstream and downstream of the nacelle being defined with reference to the flow direction of the air flow in the nacelle in direct jet operation, the upstream of the nacelle corresponding to a portion of the nacelle through which the air flow penetrates, and the downstream corresponding to an ejection area of said air flow.
The role of a thrust reverser, during landing of an aircraft, is to improve the braking capacity thereof by redirecting forward at least a portion of the thrust generated by the turbojet engine. In this phase, the thrust reverser obstructs the flow path of the cold air flow passing through the nacelle, and directs the latter forward of the nacelle, thereby generating a counter-thrust which adds to the braking of the wheels of the plane.
The means implemented to achieve this redirecting of the cold flow vary depending on the thrust reverser type. However, in all cases, the structure of a thrust reverser comprises one or more movable cowl(s) displaceable between, on the one hand, a deployed position in which they open a passage in the nacelle intended to the deflected flow, and on the other hand, a retracted position in which they close this passage. These cowls may perform a deflection function or simply a function of activating other deflecting means.
In the case of a thrust reverser with vanes, also known as a cascade thrust reverser, the redirecting of the air flow is performed by cascade vanes, the thrust reverser cowl(s) simply sliding substantially along the longitudinal axis of the nacelle in order to uncover or cover these vanes. Complementary blocking doors, also called flaps, activated by the sliding of the cowling, generally allow for a closure of the flow path downstream of the vanes so as to optimize the redirecting of the cold flow.
In such a thrust reverser 1 with vanes 3 schematically represented in FIG. 1, it is necessary to provide a seal 5 made of an elastomeric material mounted on the cowl 7 and in contact with a deflecting edge 9 when the thrust reverser is in the closed position.
In this position, the air flowing in the cold air flow path 11 under the effect of a turbojet engine fan (members which are not shown) should not be able to escape from this flow path toward the vanes 3: the seal 5 allows achieving this sealing.
An embodiment of the seal 5 of the prior art viewed in cross-section is represented in FIG. 2.
The seal 5 comprises a flexible tubular body 13 and a relatively stiff base 15. The base 15 is planar at its upper support surface 17 on which the body 13 of the seal rests, and at its lower bearing surface 19. The end portions 21 and 23 of the base 15 are curved.
The seal 5 is generally mounted in a support 25, as illustrated in FIG. 3. Such a support typically has a “C”-shaped cross-section, complementary to the shape defined by the bearing surface 19 and by the end portions 21 and 23 of the base 15 of the seal 5.
The seal support 25 has a planar surface 27 and two curved end portions 29 and 31 corresponding to the end portions 21 and 23 of the base 15 of the seal 5.
The set 33 comprising the seal 5 mounted in its support 25 is intended to be positioned between two members 35 and 37, the member 37 being the one to be sealed.
The mounting of the seal in its support is generally made by inserting the base 15 of the seal 5, manually or using a tool, into its support 25.
However, the relatively little deformable structure of the base of the seal reduces the deformation capacity of this base, which complicates the insertion operation of the seal into its support.
A solution of the prior art allows simplifying the insertion and consists in substantially reducing the length of the planar surfaces 39 and 41 of the curved end portions 29 and 31 of the seal support 25. Indeed, by substantially reducing these lengths, the end portions 21 and 23 of the base 15 of the seal 5 penetrate more easily into the curved end portions 29 and 31 of the seal support.
However, such a limited overlapping may result in a disengagement of the seal from its support. In order to avoid such a disengagement, a solution consists in bonding a portion of the base of the seal into the seal support.
For this, it is known to bond either the bearing planar surface 19 of the base 15 of the seal on the planar surface 27 of the seal support 25, or the curved end portions 21 and 29 of the seal 5 into the curved end portions 29 and 31 of said support.
These bonding operations are time-consuming, expensive and tedious, and the bonding quality, that is to say the percentage of bonded surface, cannot be properly verified once the seal is mounted in its support. Furthermore, the presence of adhesive makes the replacement operations of the seal, when worn, complicated.